Editing an imported 3D character which was made with photo shoots
It sounds like you have a 3d scan. Most likely the model will be completely unsuitable for animation in its current form.

You need to create a lower res model with topology suitable for animation using retopology. The basic idea of this is you create a new, simpler mesh, that follows the overall shape of the original mesh (usually using either the shrinkwrap modifier or the snap to surface function in edit mode).

The full details of this are too complicated for a single answer here but there are plenty of tutorials around on the net. I'm hesitant to recommend any because I haven't watched any of them myself. There is a paid CGCookie one, which will probably be decent, but I'm sure there is plenty of good free stuff on youtube.

Once this is done, you can bake normals/displacements/textures from your original model to the new model. http://www.blenderdiplom.com/en/tutorials/all-tutorials/585-normal-baking-using-the-blender-internal-renderer.html looks like a good starting point here.